The present invention relates to a vibration actuator having an electromagnetic vibrator element, a method of driving the vibration actuator, a vibration apparatus with the vibration actuator mounted thereon, and a mobile apparatus including the vibration apparatus.
In recent years, a mobile telephone apparatus as a mobile apparatus has become more and more increasingly used. Typically, the mobile telephone apparatus is equipped with an actuator for generating body-felt vibration, another actuator for generating a buzzer sound, and a loudspeaker for generating a reproduced sound or a sound corresponding to speech. Thus, the mobile telephone apparatus is operable in three vibration modes by the use of two actuators and one or more loudspeakers mounted therein.
Generally, the mobile telephone apparatus is strongly requested to be reduced in size. Therefore, attempts have been made to reduce the number of devices mounted in the mobile telephone apparatus. For example, Japanese Unexamined Patent Publication (JP-A) No. H09-70571 discloses a pager as the mobile apparatus comprising an actuator including an electromagnetic vibrator element held by two plate-like or flat elastic members having different spring constants. In the actuator, the frequency of an electric current supplied to the electromagnetic vibrator element is selected to selectively resonate, as a resonated member, one of the two flat elastic members so that vibration is generated in a resonance frequency of the resonated member. Thus, the single actuator provides both the body-felt vibration and the buzzer sound. It is therefore possible to reduce the number of devices or components mounted in the pager.
However, the above-mentioned single actuator generates no more than the body-felt vibration and the buzzer sound. No consideration is made of generation of the sound corresponding to the speech.
It is therefore an object of the present invention to provide a vibration actuator having three vibration modes.
It is another object of the present invention to provide a method of driving the above-mentioned vibration actuator.
It is still another object of the present invention to provide a vibration apparatus equipped with the above-mentioned vibration actuator.
Other objects of the present invention will become clear as the description proceeds.
According to the present invention, there is provided a vibration actuator comprising a magnetic circuit device having a magnetic gap, a supporting device for elastically supporting the magnetic circuit device, a coil inserted into the magnetic gap, and a vibration plate supporting the coil, the actuator having a first vibration mode in which the magnetic circuit device mainly vibrates to transmit vibration through the vibration plate to the outside, a second vibration mode in which the coil mainly vibrates to produce a buzzer sound through the vibration plate, and a third vibration mode in which the magnetic circuit device and the coil mainly vibrate to produce a sound corresponding to a speech through the vibration plate.
According to the present invention, there is provided a method of driving the vibration actuator, the method comprising the steps of preparing a plurality of electric signals having different frequencies and supplying one of the electric signals to the coil to select one of the first, the second, and the third vibration modes.
According to the present invention, there is provided a method of driving the vibration actuator, the method comprising the steps of preparing a plurality of electric signals having different frequencies and supplying a superposition of at least two of the electric signals to the coil to simultaneously select at least two of the first, the second, and the third vibration modes.
According to the present invention, there is provided a vibration apparatus comprising the vibration actuator and a housing containing the vibration actuator.
According to the present invention, there is provided a mobile apparatus including the vibration apparatus.